Rear gearshift mechanism for coaxial installation

ABSTRACT

A bicycle gearshift mechanism has a base element, a pivot mechanism, a movable element, and a chain guide arrangement. The pivot mechanism connects the base element to the movable element. The chain guide arrangement is connected, rotatably about a rotary axle, to the movable element. The base element comprises a first attachment end, which is coaxial with respect to the rear-wheel axle or axis, and a second attachment end for coupling to the pivot mechanism

This application claims priority to, and/or the benefit of, German patent application DE 10 2017 002 629.7, filed on Mar. 20, 2017, and German patent application DE 10 2018 001 253.1, filed on Feb. 16, 2018, the disclosure of which are all included by reference herein in their entirety.

FIELD OF THE INVENTION

The invention relates to a bicycle gearshift mechanism, and more particularly to a bicycle rear gearshift mechanism for coaxial installation on a rear-wheel axis.

BACKGROUND

Rear gearshift mechanisms are traditionally fastened to the right-hand dropout of the frame by means of a derailleur hanger. For this purpose, the derailleur hanger is, at one end thereof, fixed to the frame coaxially with respect to the rear-wheel axis and, at the other end thereof, connected to the base element (also referred to as B-knuckle) of the gearshift mechanism. The base element is rotatable relative to the derailleur hanger about the B-axle. Derailleur hangers differ from one another greatly depending on manufacturer and manner of attachment. They may be formed in one piece with the frame or may be present as a separate component. Separate derailleur hangers are clamped to the frame either by means of quick-release axles or by means of thru axles. The clamping is possible both on the frame outer side and on the frame inner side. This has the effect that, depending on the derailleur hanger used, the gearshift mechanism assumes a different position relative to the rear-wheel axis and also relative to the sprocket assembly. These differences in position in the axial direction and in the radial direction complicate the design of the gearshift mechanism and the installation thereof. The gearshift mechanism must be newly set depending on the derailleur hanger. Owing to the additional component, additional tolerances are involved, which have an adverse effect on the positioning accuracy of the gearshift mechanism.

Furthermore, the derailleur hangers, specifically as separate components, are susceptible to damage and are often unstable. In the case of large sprocket assemblies and correspondingly large gearshift mechanism dimensions, increased lever forces occur, which can often be only inadequately accommodated by an exchangeable derailleur hanger. Furthermore, the enlarged gearshift mechanism dimensions with the lengthened lever ratios additionally have an adverse effect on the positioning accuracy of the gearshift mechanism. Conflicting with this is the fact that an increased number of sprockets arranged closely adjacent to one another specifically demands increased positioning accuracy.

The rear wheel comprises inter alia a rear-wheel hub with a hollow hub axle (also referred to as hollow axle). For the fastening of the rear wheel to the frame, a separate thru axle or quick-release axle is led through the hub axle of the rear-wheel hub and is clamped to the frame.

The problems discussed are addressed in part by already known gearshift mechanisms. For example, EP 0 875 444 A1, EP 1 342 658 A1 and EP 1 764 297 A1 describe gearshift mechanisms in which the separate derailleur hanger is omitted. The rotary axle of the base element runs along the rear-wheel axis, that is to say is coaxial with respect to the latter.

Normally, the known gearshift mechanisms comprise a base element with a fastening end with an opening for receiving an axle. The fastening end is, similarly to a derailleur hanger, fastened to the frame either on the outside or on the inside. For this purpose, said fastening end is clamped to the frame in non-positively locking fashion by means of a thru axle or quick-release axle. These known coaxial designs however often have deficiencies.

One such deficiency is the lack of stability of the arrangement. Modern sprocket assemblies comprise an ever increasing number of 11 or more sprockets. To be able to operate these using the gearshift mechanism, the gearshift mechanism dimension is increased. The lever forces acting on the gearshift mechanism also increase in association with this, such that the gearshift mechanism exhibits a tendency to tilt relative to the planes of rotation of the sprockets. Only a gearshift mechanism standing exactly vertically under the sprocket assembly permits precise gearshifts.

A further such deficiency is the dependency of frame tolerances. Since conventional gearshift mechanisms are fastened directly to the frame and are referenced with respect to the latter, manufacturing tolerances of the frame also have a direct effect on the gearshift mechanism. The positioning accuracy and settability of the gearshift mechanism suffer as a result.

Furthermore, the known axially installed gearshift mechanisms are susceptible to incorrect gearshifts. Owing to their obliquely positioned linkage mechanism (oblique parallelogram), shocks in a vertical direction, such as a rise during off-road riding, can lead to a movement of the linkage mechanism and thus to undesired gearshift processes (ghost shifting). Specifically for use with large cassette spreads, oblique parallelograms exhibit only limited suitability. To be able to reach the sprockets that exhibit great differences in size, the oblique parallelogram would have to be set to an even more oblique position, and/or the gearshift mechanism dimensions would have to be increased further. Both would further increase the susceptibility to undesired gearshift processes. An additional problem of gearshift mechanisms with oblique parallelograms is that they can be set only in a complicated manner.

The problem addressed is therefore that of providing a rear gearshift mechanism which overcomes the disadvantages of the known gearshift mechanisms.

SUMMARY AND DESCRIPTION

In an embodiment, a rear gear shifting mechanism for a bicycle includes a base element, a linkage mechanism, a movable element, and a chain guide arrangement. In the embodiment the linkage mechanism connects the base element to the movable element, and the chain guide arrangement is connected, rotatably about a rotary axle axis, to the movable element. In this embodiment the base element comprises a first attachment end for coaxial installation on the rear-wheel axle axis and a second attachment end for coupling to the linkage mechanism.

In an embodiment the rear gear shifting mechanism is configured such that the first attachment end has a first arm and a second arm, which are arranged so as to be spaced apart from one another in an axial direction.

In an embodiment, the rear gear shifting mechanism is configured such that the base element, in particular the hub stop surface of the first arm, abuts in an operationally ready state axially against a hub end cap.

In an embodiment, the rear gear shifting mechanism is configured such that the linkage mechanism comprises at least one pivot axle which is oriented orthogonally with respect to the rear-wheel axis.

BRIEF DESCRIPTION OF THE DRAWING

The present invention is explained in greater detail below with reference to the appended drawings, in which:

FIG. 1 shows a perspective view of the outer side of a gearshift mechanism;

FIG. 2 shows a sectional illustration of FIG. 1 along the axis A without a hub arrangement;

FIG. 3 shows a side view of the gearshift mechanism;

FIG. 4 shows a perspective view from the inside of the base element installed on the frame;

FIG. 5 shows a perspective partial section of the base element from FIG. 4 with adapter;

FIG. 6 shows an enlarged view of FIG. 5 without a hub arrangement;

FIG. 7 shows a fully sectional illustration of the arrangement from FIG. 6;

FIG. 8 shows an exploded illustration of the base element and of the adapter;

FIG. 9a shows a perspective view from the outside of the base element;

FIG. 9b shows a perspective view from the inside of the base element;

FIG. 10 shows a partial section through a second embodiment with setting aid;

FIG. 11 shows a view from the inside of a third embodiment in the inner stop position;

FIG. 12 shows a view from the rear of the third embodiment in the outer stop position;

FIG. 13 shows a bicycle with a conventional gearshift mechanism;

FIG. 14 shows a sectional illustration of a fourth embodiment;

FIG. 15a shows a sectional illustration of a fifth embodiment;

FIG. 15b shows a perspective view from the outside of FIG. 15 a;

FIG. 16 shows an enlarged detail view from FIG. 15 b;

FIG. 17 shows selected parts from FIG. 16;

FIG. 18 shows selected parts from FIG. 16;

FIG. 19 shows an enlarged exploded illustration of the adapter of the fifth embodiment;

FIG. 20a shows a thru axle as per the fifth embodiment;

FIG. 20b shows a sectional illustration of the thru axle from FIG. 20 a;

FIG. 21 shows a sectional illustration of the entire rear-wheel axle arrangement with thru axle as per the fifth embodiment;

FIG. 22 shows a sectional illustration of selected parts of the rear-wheel axle arrangement from FIG. 21;

FIG. 23 shows a sectional illustration of selected parts from FIG. 22;

FIG. 24a shows a partially sectional illustration of selected parts of a rear-wheel axle arrangement with a thru axle as per a sixth embodiment;

FIG. 24b shows a perspective view from the outside of FIG. 24 a;

FIG. 25a shows a thru axle as per the sixth embodiment; and

FIG. 25b shows a sectional illustration of the thru axle from FIG. 25 a.

DETAILED DESCRIPTION OF THE DRAWING

A first aspect of the invention achieves the object by a rear gearshift mechanism, such as a rear derailleur, for coaxial installation on a rear wheel axle and/or axis of a bicycle. In an embodiment, the rear gear shifting mechanism for a bicycle includes a base element, a linkage mechanism, a movable element, and a chain guide arrangement. In the embodiment the linkage mechanism connects the base element to the movable element, and the chain guide arrangement is connected, rotatably about a rotary axle axis, to the movable element. In this embodiment the base element comprises a first attachment end for coaxial installation on the rear-wheel axle axis and a second attachment end for coupling to the linkage mechanism. In this embodiment, the rear gear shifting mechanism is configured such that the first attachment end has a first arm and a second arm, which are arranged so as to be spaced apart from one another in an axial direction.

The rear gearshift mechanism according to the invention is suitable for coaxial installation on a rear-wheel axis. The gearshift mechanism has a base element (also referred to as B-knuckle), a linkage mechanism, a movable element (also referred to as P-knuckle) and a chain guard arrangement. The linkage mechanism connects the base element to the movable element. The chain guard arrangement is connected, rotatably about a rotary axle (P-axle), to the movable element. The base element comprises a first attachment end, which can be installed on the bicycle frame coaxially with respect to the rear-wheel axis, and a second attachment end for coupling to the linkage mechanism. Here, the first attachment end has a first arm and a second arm which are arranged spaced apart from one another in an axial direction.

The two arms serve for the fastening of the base element to the rear-wheel axle arrangement. An advantage in this embodiment is that the two mutually spaced-apart arms of the base element ensure a stable orientation of the gearshift mechanism parallel to the plane of rotation of the sprockets, and thus perpendicular to the rear-wheel axis, in the installed state of the gearshift mechanism. Tilting of the gearshift mechanism out of said plane is prevented in an effective manner even under the action of relatively high forces. The two axially spaced-apart fastening points of the base element to the rear-wheel axle assembly can accommodate the forces acting on the gearshift mechanism much more effectively than the known gearshift mechanisms with only one fastening end.

In one refinement of the gearshift mechanism, in the installed state of the gearshift mechanism, the first arm is situated on an axial inner side of a bicycle frame and the second arm is situated on an axial outer side of the frame. In other words, this means that the rear gearshift mechanism is mounted on the frame coaxially with respect to the rear-wheel axis A. More specifically, the gearshift mechanism is installed on the right-hand dropout of the frame.

The inner side of the frame refers to that side of the frame which points in the direction of the sprocket assembly. The axial outer side refers to that side of the frame which is situated opposite the inner side and which points away from the sprocket assembly.

In one refinement of the gearshift mechanism, the first arm has a first centering opening and the second arm has a second centering opening.

In one refinement of the gearshift mechanism, the first arm has, on its axial outer side, an adapter stop surface.

In one refinement of the gearshift mechanism, the first arm has, on its axial inner side, a hub stop surface.

The two stop surfaces provide in each case one axial stop for the parts that adjoin the base element in the installed state. In the embodiment, an adapter bears against the base element from the outside, and a hub, in particular a hub end cap, bears against the base element from the inside.

In one refinement of the gearshift mechanism, the first arm has, on its axial inner side, a hub guide.

The hub guide facilitates the installation of the rear wheel, because the hub, in particular the hub end cap, can slide into its end position along the hub guide, in particular along the guide surfaces thereof which taper towards one another. The inner side of the arm refers in turn to that side of the arm which points in the direction of the sprocket assembly in the installed state of the base element. The outer side refers to that side of the arm which points away from the sprocket assembly.

In one refinement of the gearshift mechanism, the first arm has an axle opening for the leadthrough of an axle. The axle is in particular a thru axle or a quick-release axle. The diameter of the axle opening must thus be dimensioned to be larger than that of the axle in order that the latter can be led through. In the present case, the centering opening on the first arm simultaneously forms the axle opening. The two openings could however also be formed separately from one another.

The second arm, mounted on the outer side of the frame, of the base element may also have an axle opening, if the axle projects into the region of the second arm or beyond. This may apply in the case of quick-release axles. In one refinement of the gearshift mechanism, the base element has an attachment point for a cable diverter or pulley. Normally, a gearshift cable extending from the frame is led to the gearshift mechanism via the gearshift diverter.

In one refinement of the gearshift mechanism, the base element has a first receptacle for a first pivot axle of the linkage mechanism and a second receptacle for a second pivot axle of the linkage mechanism. The inner pivot arm of the linkage mechanism is rotatably connected to the base element by the first pivot axle. The outer pivot arm of the linkage mechanism is rotatably connected to the base element by the second pivot axle. For this purpose, the pivot axles are mounted in in each case one receptacle on the base element. The axle receptacles are oriented such that they can receive pivot axles oriented orthogonally with respect to the rear-wheel axis. That is to say, the receptacles or the longitudinal axes thereof are coordinated with the pivot axles of the linkage mechanism and are each oriented, exactly like the pivot axles, orthogonally with respect to the rear-wheel axis. An orientation orthogonal with respect to the rear-wheel axis construction that the longitudinal axes of the first and second receptacles of the base element each lie in a plane which intersects the rear-wheel axis, or a geometric axis A running along the rear-wheel axis, at a right angle. Small deviations owing to the normal manufacturing tolerances are self-evidently possible. This orientation of the receptacles on the base element permits the coupling to a straight linkage mechanism (straight four-joint parallelogram). The attachment parts for the cable diverter may either be formed in one piece with the base element or may be connected as a separate part to said base element. The same applies to the inner and outer axle receptacles.

The base element itself may also be of single-part or multi-part form. A single-piece base element manufactured from metal, in particular milled from aluminum, is particularly stable and can be manufactured with high precision. Other materials such as fiber-reinforced plastics may however also be used for parts or for the entire base element.

In one refinement, the gearshift mechanism has an adapter which comprises a screw connection. The screw connection is formed in particular by a bolt with an external thread and a nut with an internal thread. The gearshift mechanism is fixable to the frame by use of the adapter.

The adapter is insertable into a frame opening. In other words, the adapter extends through the frame opening. The frame opening may differ depending on the axle used. Thru axles are normally inserted into openings that are enclosed by the frame. Quick-release axles are, by contrast, normally inserted from below into a slot-like opening.

The adapter is fixable on the frame using the screw connection. For this purpose, the adapter has, at its ends thereof, external diameters which are dimensioned to be larger than the diameter of the frame opening. One end of the adapter lies against the inner side of the frame and the other end lies against the outer side. By tightening the screw connection, the adapter is fixable relative to the frame both in an axial direction and in rotation. The bolt head of the bolt and the nut are dimensioned to be larger than the frame opening and bare against the inner side and outer side thereof. The nut has a knurled contact surface which, in the fully installed state, bears in non-positively locking and positively locking fashion against the frame.

In one refinement of the gearshift mechanism, the bolt has a bolt body with a contact region and a compensation region. The contact region bears against the internal diameter of the frame opening. The compensation region tapers for example in a conical manner and exhibits a slightly greater amount of play relative to the frame opening. Owing to the increased play, the bolt and thus the adapter as a whole can be aligned relative to the frame opening. Frame inaccuracies can thus be compensated. The adapter can be aligned coaxially with the rear-wheel axis A even if the frame opening axis deviates therefrom owing to tolerances.

In one refinement of the gearshift mechanism, the adapter has an axle opening in which an internal thread is arranged. The counterpart thread of a thru axle can be screwed into the internal thread. In particular, the bolt has the axle opening with the internal thread.

The external thread of the bolt and the internal thread of the bolt are arranged in regions along the bolt longitudinal axis which do not overlap or overlap only slightly. The forces transmitted to the bolt by the thread can be accommodated most effectively with this arrangement.

In one refinement of the gearshift mechanism, a first external diameter of the adapter is coordinated with an internal diameter of the first centering opening of the base element, and a second external diameter of the adapter is coordinated with an internal diameter of the second centering opening of the base element.

In particular, the first external diameter of a centering foot of the bolt is coordinated with the first centering opening. A second external diameter of the bolt head is coordinated with the second centering opening.

A clearance fit between the adapter and the centering openings of the base element makes it possible for the adapter to be inserted into the base element and thus for the base element to be centered relative to the adapter.

In one refinement of the gearshift mechanism, the adapter, in particular the stop surface of the bolt, bears in the installed state against the adapter stop surface of the base element. An axial movement of the adapter relative to the base element in an inwards direction is thereby limited.

In one refinement of the gearshift mechanism, the base element has a stop and the adapter has a counterpart stop. If the adapter is rotated clockwise, it strikes with its counterpart stop against the stop of the base element and rotates the latter conjointly. The rotation of the adapter relative to the base element is limited by the stops. The stop on the base element is formed in particular by two pins on the first arm of the base element, which interact with two projections on the nut.

A second aspect of the invention achieves the object using a rear gearshift mechanism for coaxial installation. In an embodiment, a rear gear shifting mechanism for a bicycle includes a base element, a linkage mechanism, a movable element, and a chain guide arrangement. In the embodiment the linkage mechanism connects the base element to the movable element, and the chain guide arrangement is connected, rotatably about a rotary axle axis, to the movable element. In this embodiment the base element comprises a first attachment end for coaxial installation on the rear-wheel axle axis and a second attachment end for coupling to the linkage mechanism. In an embodiment, the rear gear shifting mechanism is configured such that the base element, in particular the hub stop surface of the first arm, abuts in an operationally ready state axially against a hub end cap.

According to the second aspect of the invention, the rear gearshift mechanism according to the invention is suitable for coaxial installation on a rear-wheel axle. The gearshift mechanism has a base element, a linkage mechanism, a movable element and a chain guide arrangement. The linkage mechanism connects the base element to the movable element. The chain guide element is connected, rotatably about a rotary axle P, to the movable element. The base element abuts in an operationally ready state axially against a hub end cap. In particular, the hub stop surface of the first arm of the base element is supported on the hub end cap.

The gearshift mechanism is thus referenced with respect to the hub in an axial direction.

In one refinement of the gearshift mechanism, the first arm of the base element is in an operationally ready state arranged between the hub end cap and the adapter. In particular, the first arm of the base element is fixed in non-positively locking and rotationally fixed fashion between the hub end cap and the adapter.

The non-positive locking is generated by tightening an axle, in particular the thru axle. Here, the base element is clamped between the hub end cap and the adapter and is at the same time oriented orthogonally with respect to the hub axle. The conventional referencing of the gearshift mechanism with respect to the frame is omitted, such that manufacturing tolerances of the frame no longer have an adverse effect on the positioning and setting of the gearshift mechanism. The base element is ideally positioned with a degree of play with respect to the frame, such that it does not quite make contact with the latter.

In the operationally ready state, the gearshift mechanism and the rear wheel are installed, and the thru axle is tightened. The base element is then both fixed in an axial direction and installed rotationally conjointly on the rear-wheel axle arrangement. Furthermore, the base element engages around the adapter and is centered relative to the latter.

As an alternative to the hub end cap, it is also possible in the case of other hub constructions for an axle nut or some other similar functional part to abut against the base element. It is important that said functional part permits perpendicular orientation of the base element and thus of the gearshift mechanism relative to the rear-wheel axis A.

A third aspect of the invention achieves the object using a rear gearshift mechanism for coaxial installation. In an embodiment, a rear gear shifting mechanism for a bicycle includes a base element, a linkage mechanism, a movable element, and a chain guide arrangement. In the embodiment the linkage mechanism connects the base element to the movable element, and the chain guide arrangement is connected, rotatably about a rotary axle axis, to the movable element. In this embodiment the base element comprises a first attachment end for coaxial installation on the rear-wheel axle axis and a second attachment end for coupling to the linkage mechanism. In an embodiment, the rear gear shifting mechanism is configured such that the linkage mechanism comprises at least one pivot axle which is oriented orthogonally with respect to the rear-wheel axis.

According to the third aspect of the invention, the rear gearshift mechanism according to the invention is suitable for coaxial installation on a rear-wheel axis. The gearshift mechanism has a base element, a linkage mechanism, a movable element and a chain guide arrangement. The linkage mechanism connects the base element to the movable element. The chain guide element is connected, rotatably about a rotary axle P, to the movable element. The linkage mechanism comprises at least one pivot axle which is oriented orthogonally with respect to the rear-wheel axis A. The orthogonal orientation of the pivot axle is in this case independent of the selected relative position of the gearshift mechanism.

That is to say, the pivot axle lies in a plane that intersects the rear-wheel axle, or a geometric axis A running along the rear-wheel axle, at a right angle. Owing to manufacturing tolerances and installation inaccuracies, said angle may also deviate slightly. The rear-wheel axle, the hub axle, the rotary axle of the sprocket and the installed base element extend on the same axis A.

In one refinement of the gearshift mechanism, the linkage mechanism is formed as a four-joint parallelogram with four pivot axles. All four pivot axles are oriented orthogonally with respect to the rear-wheel axis.

Owing to the pivot axles oriented orthogonally with respect to the rear-wheel axis, the linkage mechanism now moves only in the axial direction. Shocks acting on the gearshift mechanism, such as occur when riding on uneven terrain, can be accommodated by the linkage mechanism without moving the latter. Undesired gearshifts are prevented.

Furthermore, a gearshift mechanism with a straight four-joint parallelogram can be installed and set particularly easily. The installation and setting will be described in detail further below.

In one refinement of the gearshift mechanism, a first pivot axle rotatably connects an inner pivot arm of the linkage mechanism to an inner receptacle on the base element. A second pivot axle rotatably connects an outer pivot arm of the linkage mechanism to an outer receptacle on the base element. The receptacles are aligned axially with the pivot axles. The longitudinal axes of the receptacles thus run, exactly like the received pivot axles, orthogonally with respect to the rear-wheel axis. The receptacles are arranged on the second attachment end of the base element, which points in the direction of the linkage mechanism.

In one refinement of the gearshift mechanism, the chain guide arrangement comprises an upper chain guide roller. The upper chain guide roller is arranged so as to be rotatable with the movable element with a constant upper spacing to the rotary axle P of the chain guide arrangement. The gearshift mechanism furthermore comprises a lower chain guide roller which is arranged so as to be rotatable with the movable element with a constant lower spacing to the rotary axle P of the chain guide arrangement.

The upper spacing between the upper chain guide roller and the rotary axle P is dimensioned to be shorter than the lower spacing between the lower chain guide roller and the rotary axle P.

Aspects of the invention may be considered and implemented separately from one another and also in a combination. The embodiments illustrated show a combination of aspects. Embodiments would however also be conceivable which realize only one or two of the stated aspects. An example of this is a gearshift mechanism which realizes only the first two aspects but not the third aspect and which uses an oblique parallelogram, or slanted parallelogram, mechanism instead of a straight parallelogram mechanism. An alternative to this is a gearshift mechanism which realizes only the second and/or third aspect but not the first aspect and which comprises a base element with only one rather than two arms.

An oblique parallelogram would basically be conceivable but would have to be correspondingly adapted. This would be a possibility specifically in the case of racing bicycles, which are subjected to less severe shocks and which normally comprise sprocket assemblies with a smaller spread.

Owing to the improved positioning accuracy of the gearshift mechanism according to the invention relative to the sprocket assembly, it is conceivable to omit the conventional limit screws for the inner and outer stops of the gearshift mechanism. Said limit screws have hitherto been used to set the maximum movement of the gearshift mechanism in an axial direction and to prevent the chain guide arrangement from being moved axially beyond the sprocket planes of the larger sprocket (the inside) and of the smallest sprocket (the outside). The adjustment and readjustment of the limit screws is susceptible to faults. Fixed limit stops on the chain guide arrangement would be one possibility for replacing the screws. It would be possible for a first limit stop to interact with the largest sprocket in order to limit the axial movement towards the inside. It would be possible for a second limit stop to interact with the base element in order to limit the axial movement to the outside (cf. FIGS. 11 and 12).

According to one embodiment of the rear gearshift mechanism, the gearshift mechanism, in particular the movable element, has an arresting element. The arresting element makes it possible for the preloaded chain guide arrangement to be fixed relative to the movable element for the purposes of setting the gearshift mechanism. The setting process will be discussed in conjunction with the figures.

In one embodiment of the rear gearshift mechanism, the first attachment end of the base element has a first centering opening which interacts in the operationally ready state with a centering surface of the thru axle. The direct interaction of the first centering opening of the base element and of the centering surface of the thru axle leads to the direct centering of the base element on the thru axle. In other words, the base element is referenced with respect to the thru axle, such that manufacturing tolerances of the frame do not have an effect on the centering of the gearshift mechanism.

In one embodiment of the rear gearshift mechanism, a first limit stop is arranged on the movable element or on the chain guide arrangement. The first or inner limit stop is designed to interact with a sprocket assembly in an inner maximum position of the gearshift mechanism. The inner limit stop of the gearshift mechanism delimits an axial movement of the gearshift mechanism towards the inside. In the inner maximum position of the gearshift mechanism, a chain is situated on the inner most, that is to say largest, sprocket of the sprocket assembly. The first limit stop prevents the gearshift mechanism from being able to be moved further in an axial direction beyond the intended inner maximum position. A collision of the gearshift mechanism with the bicycle spokes is prevented.

In one embodiment of the rear gearshift mechanism, an outer limit stop is arranged on the chain guide arrangement. The second or outer limit stop is designed to interact, in an outer maximum position of the gearshift mechanism, with the base element. The outer limit stop of the gearshift mechanism limits an axial movement of the gearshift mechanism towards the outside. In the outer maximum position of the gearshift mechanism, a chain is situated on the outermost, that is to say smallest, sprocket of the sprocket assembly. The second limit stop prevents the gearshift mechanism from being able to be moved further in an axial direction beyond the intended outer maximum position.

The limit stops make it possible to omit conventional maintenance-intensive limit screws.

The described gearshift mechanism designs permit both radial centering of the base element on the adapter, more specifically on the bolt foot of the adapter, and radial centering of the base element directly on a centering surface of the thru axle. This has the advantage that the same base element can be used with thru axles of different diameter. The gearshift mechanism can remain largely unchanged. Only the adapter, in particular the bolt, for the fastening of the gearshift mechanism to the frame has to be adapted to the external dimensions of the respectively used thru axle. Common external diameters for the thru axles are 12 mm and 15 mm. This embodiment also enables the same hub arrangement to be adapted quickly and inexpensively to different conditions merely by exchanging the thru axle. For example, to increase the stiffness of the rear-wheel axle arrangement, a 12 mm thru axle can be replaced with a 15 mm thru axle. Different wall thickness configurations of the 15 mm thru axle furthermore permit adaptation to particularly lightweight or particularly rigid rear-wheel axle arrangements.

A fourth aspect of the invention constitutes an alternative solution for referencing of the gearshift mechanism that is independent of frame tolerances. In one embodiment, the rear gearshift mechanism is suitable for coaxial installation on a rear-wheel axis. The gearshift mechanism has a base element, a linkage mechanism, a movable element and a chain guide arrangement. The linkage mechanism connects the base element to the movable element. The chain guide element is connected, rotatably about a rotary axle P, to the movable element. The base element comprises a first attachment end for coaxial installation on the rear-wheel axis and a second attachment end for coupling to the linkage mechanism. The first attachment end of the base element has a first centering opening for the purposes of directly centering the base element on a thru axle.

In one embodiment of the rear gearshift mechanism, the first centering opening is formed in a first arm of the base element.

In the operationally ready state, the first centering opening of the base element interacts directly with the screwed-in thru axle, in particular with a centering surface of the thru axle. The direct interaction of the first centering opening of the base element and the centering surface of the thru axle leads to the centering of the base element directly on the thru axle. In other words, the base element is referenced with respect to the thru axle, such that manufacturing tolerances of the frame do not have an effect on the centering of the gearshift mechanism.

In one embodiment, the base element has a second arm which is arranged so as to be spaced apart in an axial direction from the first arm. The second arm has a second centering opening. In the operationally ready state, the first centering opening of the first arm interacts with the centering surface of the thru axle and the second centering opening of the second arm interacts with the adapter, in particular with the external diameter of the bolt head of the adapter. This arrangement permits precise orientation of the rear gearshift mechanism perpendicular to the rear-wheel axis.

In one embodiment of the rear gearshift mechanism, the base element is designed to abut in the operationally ready state axially against a hub end cap. In particular, an axial hub stop surface of the first arm of the base element is designed to abut against the hub end cap.

In one embodiment of the rear gearshift mechanism, the linkage mechanism comprises at least one pivot axle which is oriented orthogonally with respect to the rear-wheel axis. The advantages of orthogonally oriented gearshift mechanisms have already been discussed in conjunction with the preceding embodiments.

A fifth aspect of the invention relates to a thru axle for screwing into a rear gearshift mechanism, in particular into a gearshift mechanism for coaxial installation as has been described above. According to the fifth aspect, the thru axle is suitable for screwing into a rear gearshift mechanism. The thru axle has a first thru axle end and a second thru axle end. The thru axle has, on an outer circumferential surface in the region of the second end, an external thread and a centering surface. The centering surface serves for the centering of the base element directly on the thru axle. In the screwed-in state, the centering surface of the thru axle interacts with a first centering opening of the base element for the purposes of directly centering the base element on the thru axle.

In one embodiment, the thru axle is of hollow form. The thru axle has a greater wall thickness in the region of the external thread and/or of the centering surface than in other regions.

A sixth aspect of the invention provides an adequately stiff and lightweight rear-wheel axle arrangement for a bicycle (stiffness to weight ratio). This embodiment is of importance in particular for MTBs and E-MTBs. Rear-wheel axle arrangements known from the prior art exhibit a tendency for the hub axle (hollow axle) to break. This is inter alia because the hub axle is subjected to high maximum bending stresses in relation to the thru axle. It has proven to be advantageous for the acting stresses and forces to be distributed as uniformly as possible on the hub axle and the thru axle and for a breakage of one of the two components to thus be prevented. Both the hub axle and the thru axle are loaded more uniformly, and are no longer overloaded on one side. A uniform distribution is achieved in particular if the ratio of the geometrical moment of inertia of the hub axle to the geometrical moment of inertia of the thru axle is relatively balanced. The geometrical moment of inertia ratio of hub axle to thru axle lies in the range from approximately 0.8 to 1.5, and is in particular approximately 1.1. A positive effect is realized inter alia by the fact that the hub axle is subjected to compressive load and the thru axle is subjected to tensile load. The compressive and tensile stresses are superposed on the bending stresses, and partially cancel one another out.

According to the sixth aspect, a rear-wheel axle arrangement for a bicycle comprises a hub arrangement and a thru axle. The hub arrangement comprises a rear-wheel hub (also referred to as hub sleeve) which is rotatable about the rear-wheel axis, a hollow hub axle (also referred to as hollow axle), and a hub bearing arrangement. The hub bearing arrangement enables the rear-wheel hub to be mounted so as to be rotatable relative to the hub axle about the rear-wheel axis. The hollow thru axle is, for the purposes of fixing the hub arrangement to a bicycle frame, designed such that it can be inserted into the hollow hub axle and screwed into a rear gearshift mechanism. The hollow thru axle has, at least in the region of the hub bearing, a wall thickness which is dimensioned to be at least as great as a wall thickness of the hub axle.

Owing to the considerably increased geometrical moment of inertia, thru axles with an increased external diameter of 15 mm have a positive effect on the stiffness of the entire rear-wheel axle arrangement. The thru axle is likewise a load-bearing component. The increased diameter of the thru axle contributes to a balanced geometrical moment of inertia of hub axle and thru axle. In particular, rear-wheel axle arrangements have proven to be successful which have a hub axle with an external diameter of approximately 17 mm and an internal diameter of approximately 15 mm combined with a thru axle with an external diameter of approximately 15 mm. The diameter of the thru axle and of the hub axle are coordinated with one another such that the thru axle can be inserted into the hub axle with a clearance fit. The thru axle may, depending on the field of use, have for example a wall thickness of 1.5 mm (standard), 1 mm (lightweight) and 2 mm (E-bike). These configurations lead to a balanced load on hub axle and thru axle. The different thru axles may be used with the same hub axle depending on the field of use. In other words, the same hub arrangement can be inexpensively and quickly adapted by exchanging the thru axle (modular principle).

The aspects of the invention may be considered and implemented separately from one another or in a combination of multiple aspects.

The invention furthermore relates to a bicycle drive which comprises a gearshift mechanism according to the invention, a multi-sprocket arrangement with eleven, twelve or more sprockets, a bicycle chain and a chain ring arrangement with in particular exactly one chain ring. In an embodiment the gearshift mechanism may be electrically controlled. Likewise, in the case of multiple chain rings, the derailleur may also be electrically controlled. Wireless control of the gearshift mechanism and/or of the derailleur is particularly advantageous. Electrically controlled gearshift mechanisms commonly comprise a transmission unit and a battery. It would be possible for the transmission unit and/or battery to be arranged in space-saving fashion in a cavity of the base element, for example between the two arms of the base element. At this position, they would be protected against external action by the structure of the base element, and immovable relative to the frame.

At least one sprocket of the sprocket arrangement may have a sequence of a thin tooth, a thick tooth and a further thin tooth. Here, a thick tooth is designed to be of such a thickness in an axial direction that, although it can engage into an outer link pair of the chain, it cannot engage into an inner link pair. This has a positive effect on the chain guidance. The sequence may repeat multiple times along the circumference of a sprocket. In the case of sprockets with an even number of teeth, it is also possible for all of the teeth to be alternately thin and thick. The axial thickening may be realized either on both sides of the sprocket or only on one side. The thickening is preferably arranged only on the rear side of the sprocket. It is of particular significance in particular on the two largest sprockets, because it is there that the chain skew is at its most pronounced (cf. FIG. 11 with thick and thin teeth on the largest sprocket 12). As a result of the better guidance of the chain, the adverse consequences of the chain skew at the relatively large sprockets are minimized. The chain ring may also have alternating thick and thin teeth which serve for improved chain guidance.

The object is achieved by use of a rear gearshift mechanism for coaxial installation.

In an embodiment, the gearshift mechanism has a base element (also referred to as B-knuckle), a linkage mechanism, a movable element (also referred to as P-knuckle) and a chain guard arrangement. The linkage mechanism connects the base element to the movable element. The chain guard arrangement is connected, rotatably about a rotary axle (P-axle), to the movable element. The base element comprises a first attachment end, which can be installed on the bicycle frame coaxially with respect to the rear-wheel axis, and a second attachment end for coupling to the linkage mechanism. Here, the first attachment end has a first arm and a second arm which are arranged spaced apart from one another in an axial direction.

The two arms serve for the fastening of the base element to the rear-wheel axle arrangement. An advantage in this embodiment is that the two mutually spaced-apart arms of the base element ensure a stable orientation of the gearshift mechanism parallel to the plane of rotation of the sprockets, and thus perpendicular to the rear-wheel axis, in the installed state of the gearshift mechanism. Tilting of the gearshift mechanism out of said plane is prevented in an effective manner even under the action of relatively high forces. The two axially spaced-apart fastening points of the base element to the rear-wheel axle arrangement can accommodate the forces acting on the gearshift mechanism much more effectively than the known gearshift mechanisms with only one fastening end.

In one refinement of the gearshift mechanism, in the installed state of the gearshift mechanism, the first arm is situated on an axial inner side of a bicycle frame and the second arm is situated on an axial outer side of the frame. In other words, this means that the rear gearshift mechanism is mounted on the frame coaxially with respect to the rear-wheel axis A. More specifically, the gearshift mechanism is installed on the right-hand dropout of the frame.

The inner side of the frame refers to that side of the frame which points in the direction of the sprocket assembly. The axial outer side refers to that side of the frame which is situated opposite the inner side and which points away from the sprocket assembly.

In one refinement of the gearshift mechanism, the first arm has a first centering opening and the second arm has a second centering opening.

In one refinement of the gearshift mechanism, the first arm has, on its axial outer side, an adapter stop surface.

In one refinement of the gearshift mechanism, the first arm has, on its axial inner side, a hub stop surface.

The two stop surfaces provide in each case one axial stop for the parts that adjoin the base element in the installed state. In the embodiment, an adapter bears against the base element from the outside, and a hub, in particular a hub end cap, bears against the base element from the inside.

In one refinement of the gearshift mechanism, the first arm has, on its axial inner side, a hub guide.

The hub guide facilitates the installation of the rear wheel, because the hub, in particular the hub end cap, can slide into its end position along the hub guide, in particular along the guide surfaces thereof which taper towards one another. The inner side of the arm refers in turn to that side of the arm which points in the direction of the sprocket assembly in the installed state of the base element. The outer side refers to that side of the arm which points away from the sprocket assembly.

In one refinement of the gearshift mechanism, the first arm has an axle opening for the leadthrough of an axle. The axle is in particular a thru axle or a quick-release axle. The diameter of the axle opening must thus be dimensioned to be larger than that of the axle in order that the latter can be led through. In the present case, the centering opening on the first arm simultaneously forms the axle opening. The two openings could however also be formed separately from one another.

The second arm, mounted on the outer side of the frame, of the base element may also have an axle opening, if the axle projects into the region of the second arm or beyond. This may apply in the case of quick-release axles. In one refinement of the gearshift mechanism, the base element has an attachment point for a cable diverter. Normally, a gearshift cable extending from the frame is led to the gearshift mechanism via the gearshift diverter.

In one refinement of the gearshift mechanism, the base element has a first receptacle for a first pivot axle of the linkage mechanism and a second receptacle for a second pivot axle of the linkage mechanism. The inner pivot arm of the linkage mechanism is rotatably connected to the base element using the first pivot axle. The outer pivot arm of the linkage mechanism is rotatably connected to the base element using the second pivot axle. For this purpose, the pivot axles are mounted in in each case one receptacle on the base element. The axle receptacles are oriented such that they can receive pivot axles oriented orthogonally with respect to the rear-wheel axis. That is to say, the receptacles or the longitudinal axes thereof are coordinated with the pivot axles of the linkage mechanism and are each oriented, exactly like the pivot axles, orthogonally with respect to the rear-wheel axis. An orientation orthogonal with respect to the rear-wheel axis construction that the longitudinal axes of the first and second receptacles of the base element each lie in a plane which intersects the rear-wheel axis, or a geometric axis A running along the rear-wheel axle arrangement, at a right angle. Small deviations owing to the normal manufacturing tolerances are self-evidently possible. This orientation of the receptacles on the base element permits the coupling to a straight linkage mechanism (straight four-joint parallelogram). The attachment parts for the cable diverter may either be formed in one piece with the base element or may be connected as a separate part to said base element. The same applies to the inner and outer axle receptacles.

The base element itself may also be of single-part or multi-part form. A single-piece base element manufactured from metal, in particular milled from aluminum, is particularly stable and can be manufactured with high precision. Other materials such as fiber-reinforced plastics may however also be used for parts or for the entire base element.

In one refinement, the gearshift mechanism has an adapter which comprises a screw connection. The screw connection is formed in particular by a bolt with an external thread and a nut with an internal thread. The gearshift mechanism is fixable to the frame by the adapter.

The adapter is insertable into a frame opening. In other words, the adapter extends through the frame opening. The frame opening may differ depending on the axle used. Thru axles are normally inserted into openings that are enclosed by the frame. Quick-release axles are, by contrast, normally inserted from below into a slot-like opening.

The adapter is fixable on the frame by the screw connection. For this purpose, the adapter has, at its ends thereof, external diameters which are dimensioned to be larger than the diameter of the frame opening. One end of the adapter lies against the inner side of the frame and the other end lies against the outer side. By tightening the screw connection, the adapter is fixable relative to the frame both in an axial direction and in rotation. The bolt head of the bolt and the nut are dimensioned to be larger than the frame opening and bare against the inner side and outer side thereof. The nut has a knurled contact surface which, in the fully installed state, bears in non-positively locking and positively locking fashion against the frame.

In one refinement of the gearshift mechanism, the bolt has a bolt body with a contact region and a compensation region. The contact region bears against the internal diameter of the frame opening. The compensation region tapers for example in a conical manner and exhibits a slightly greater amount of play relative to the frame opening. Owing to the increased play, the bolt and thus the adapter as a whole can be aligned relative to the frame opening. Frame inaccuracies can thus be compensated. The adapter can be aligned coaxially with the rear-wheel axis A even if the frame opening axis deviates therefrom owing to tolerances.

In one refinement of the gearshift mechanism, the adapter has an axle opening in which an internal thread is arranged. The counterpart thread of a thru axle can be screwed into the internal thread. In particular, the bolt has the axle opening with the internal thread.

The external thread of the bolt and the internal thread of the bolt are arranged in regions along the bolt longitudinal axis which do not overlap or overlap only slightly. The forces transmitted to the bolt by the thread can be accommodated most effectively with this arrangement.

In one refinement of the gearshift mechanism, a first external diameter of the adapter is coordinated with an internal diameter of the first centering opening of the base element, and a second external diameter of the adapter is coordinated with an internal diameter of the second centering opening of the base element.

In particular, the first external diameter of a centering foot of the bolt is coordinated with the first centering opening. A second external diameter of the bolt head is coordinated with the second centering opening.

A clearance fit between the adapter and the centering openings of the base element makes it possible for the adapter to be inserted into the base element and thus for the base element to be centered relative to the adapter.

In one refinement of the gearshift mechanism, the adapter, in particular the stop surface of the bolt, bears in the installed state against the adapter stop surface of the base element. An axial movement of the adapter relative to the base element in an inwards direction is thereby limited.

In one refinement of the gearshift mechanism, the base element has a stop and the adapter has a counterpart stop. If the adapter is rotated clockwise, it strikes with its counterpart stop against the stop of the base element and rotates the latter conjointly. The rotation of the adapter relative to the base element is limited by the stops. The stop on the base element is formed in particular by two pins on the first arm of the base element, which interact with two projections on the nut.

A second aspect of the invention achieves the object by use of a rear gearshift mechanism for coaxial installation.

According to the second aspect of the invention, the rear gearshift mechanism according to the invention is suitable for coaxial installation on a rear-wheel axle arrangement. The gearshift mechanism has a base element, a linkage mechanism, a movable element and a chain guide arrangement. The linkage mechanism connects the base element to the movable element. The chain guide element is connected, rotatably about a rotary axle P, to the movable element. The base element abuts in an operationally ready state axially against a hub end cap. In particular, the hub stop surface of the first arm of the base element is supported on the hub end cap.

The gearshift mechanism is thus referenced with respect to the hub in an axial direction.

In one refinement of the gearshift mechanism, the first arm of the base element is in an operationally ready state arranged between the hub end cap and the adapter. In particular, the first arm of the base element is fixed in non-positively locking and rotationally fixed fashion between the hub end cap and the adapter.

The non-positive locking is generated by tightening an axle, in particular the thru axle. Here, the base element is clamped between the hub end cap and the adapter and is at the same time oriented orthogonally with respect to the hub axle. The conventional referencing of the gearshift mechanism with respect to the frame is omitted, such that manufacturing tolerances of the frame no longer have an adverse effect on the positioning and setting of the gearshift mechanism. The base element is ideally positioned with a degree of play with respect to the frame, such that it does not quite make contact with the latter.

In the operationally ready state, the gearshift mechanism and the rear wheel are installed, and the thru axle is tightened. The base element is then both fixed in an axial direction and installed rotationally conjointly on the rear-wheel axle arrangement. Furthermore, the base element engages around the adapter and is centered relative to the latter.

As an alternative to the hub end cap, it is also possible in the case of other hub constructions for an axle nut or some other similar functional part to abut against the base element. It is important that said functional part permits perpendicular orientation of the base element and thus of the gearshift mechanism relative to the rear-wheel axis A.

A third aspect of the invention achieves the object by use of a rear gearshift mechanism for coaxial installation.

According to the third aspect of the invention, the rear gearshift mechanism according to the invention is suitable for coaxial installation on a rear-wheel axis. The gearshift mechanism has a base element, a linkage mechanism, a movable element and a chain guide arrangement. The linkage mechanism connects the base element to the movable element. The chain guide element is connected, rotatably about a rotary axle P, to the movable element. The linkage mechanism comprises at least one pivot axle which is oriented orthogonally with respect to the rear-wheel axis A. The orthogonal orientation of the pivot axle is in this case independent of the selected relative position of the gearshift mechanism.

That is to say, the pivot axle lies in a plane that intersects the rear-wheel axis, or a geometric axis A running along the rear-wheel axis, at a right angle. Owing to manufacturing tolerances and installation inaccuracies, said angle may also deviate slightly. The rear-wheel axle, the hub axle, the rotary axle of the sprocket and the installed base element extend on the same axis A.

In one refinement of the gearshift mechanism, the linkage mechanism is formed as a four-joint parallelogram with four pivot axles. All four pivot axles are oriented orthogonally with respect to the rear-wheel axis.

Owing to the pivot axles oriented orthogonally with respect to the rear-wheel axis, the linkage mechanism now moves only in the axial direction. Shocks acting on the gearshift mechanism, such as occur when riding on uneven terrain, can be accommodated by the linkage mechanism without moving the latter. Undesired gearshifts are prevented.

Furthermore, a gearshift mechanism with a straight four-joint parallelogram can be installed and set particularly easily. The installation and setting will be described in detail further below.

In one refinement of the gearshift mechanism, a first pivot axle rotatably connects an inner pivot arm of the linkage mechanism to an inner receptacle on the base element. A second pivot axle rotatably connects an outer pivot arm of the linkage mechanism to an outer receptacle on the base element. The receptacles are aligned axially with the pivot axles. The longitudinal axes of the receptacles thus run, exactly like the received pivot axles, orthogonally with respect to the rear-wheel axis. The receptacles are arranged on the second attachment end of the base element, which points in the direction of the linkage mechanism.

In one refinement of the gearshift mechanism, the chain guide arrangement comprises an upper chain guide roller. The upper chain guide roller is arranged so as to be rotatable with the movable element with a constant upper spacing to the rotary axle P of the chain guide arrangement. The gearshift mechanism furthermore comprises a lower chain guide roller which is arranged so as to be rotatable with the movable element with a constant lower spacing to the rotary axle P of the chain guide arrangement.

The upper spacing between the upper chain guide roller and the rotary axle P is dimensioned to be shorter than the lower spacing between the lower chain guide roller and the rotary axle P.

Aspects of the invention may be considered and implemented separately from one another and also in a combination of aspects. The embodiments shown show a combination of aspects. Embodiments would however also be conceivable which realize only one or two of the stated aspects. An example of this is a gearshift mechanism which realizes only two aspects and/or which uses an oblique parallelogram mechanism instead of a straight parallelogram mechanism. An alternative to this is a gearshift mechanism which realizes only the second and/or third aspect but not the first aspect and which comprises a base element with only one rather than two arms.

An oblique parallelogram would basically be conceivable but would have to be correspondingly adapted. This would be a possibility specifically in the case of racing bicycles, which are subjected to less severe shocks and which normally comprise sprocket assemblies with a smaller spread.

Owing to the improved positioning accuracy of the gearshift mechanism according to the invention relative to the sprocket assembly, it is conceivable to omit the conventional limit screws for the inner and outer stops of the gearshift mechanism. Said limit screws have hitherto been used to set the maximum movement of the gearshift mechanism in an axial direction and to prevent the chain guide arrangement from being moved axially beyond the sprocket planes of the larger sprocket (the inside) and of the smallest sprocket (the outside). The adjustment and readjustment of the limit screws is susceptible to faults. Fixed limit stops on the chain guide arrangement would be one possibility for replacing the screws. It would be possible for a first limit stop to interact with the largest sprocket in order to limit the axial movement towards the inside. It would be possible for a second limit stop to interact with the base element in order to limit the axial movement to the outside (cf. FIGS. 11 and 12).

According to one embodiment of the rear gearshift mechanism, the gearshift mechanism, in particular the movable element, has an arresting element. The arresting element makes it possible for the preloaded chain guide arrangement to be fixed relative to the movable element for the purposes of setting the gearshift mechanism. The setting process is discussed in conjunction with the figures.

In one embodiment of the rear gearshift mechanism, the first attachment end of the base element has a first centering opening which interacts in the operationally ready state with a centering surface of the thru axle. The direct interaction of the first centering opening of the base element and of the centering surface of the thru axle leads to the direct centering of the base element on the thru axle. In other words, the base element is referenced with respect to the thru axle, such that manufacturing tolerances of the frame do not have an effect on the centering of the gearshift mechanism.

In one embodiment of the rear gearshift mechanism, a first limit stop is arranged on the movable element or on the chain guide arrangement. The first or inner limit stop is designed to interact with a sprocket assembly in an inner maximum position of the gearshift mechanism. The inner limit stop of the gearshift mechanism delimits an axial movement of the gearshift mechanism towards the inside. In the inner maximum position of the gearshift mechanism, a chain is situated on the inner most, that is to say largest, sprocket of the sprocket assembly. The first limit stop prevents the gearshift mechanism from being able to be moved further in an axial direction beyond the intended inner maximum position. A collision of the gearshift mechanism with the bicycle spokes is prevented.

In one embodiment of the rear gearshift mechanism, an outer limit stop is arranged on the chain guide arrangement. The second or outer limit stop is designed to interact, in an outer maximum position of the gearshift mechanism, with the base element. The outer limit stop of the gearshift mechanism limits an axial movement of the gearshift mechanism towards the outside. In the outer maximum position of the gearshift mechanism, a chain is situated on the outermost, that is to say smallest, sprocket of the sprocket assembly. The second limit stop prevents the gearshift mechanism from being able to be moved further in an axial direction beyond the intended outer maximum position.

The limit stops make it possible to omit conventional maintenance-intensive limit screws.

The described gearshift mechanism designs permit both radial centering of the base element on the adapter, more specifically on the bolt foot of the adapter, and radial centering of the base element directly on a centering surface of the thru axle. This has the advantage that the same base element can be used with thru axles of different diameter. The gearshift mechanism can remain largely unchanged. Only the adapter, in particular the bolt, for the fastening of the gearshift mechanism to the frame has to be adapted to the external dimensions of the respectively used thru axle. Common external diameters for the thru axles are 12 mm and 15 mm. This embodiment also enables the same hub arrangement to be adapted quickly and inexpensively to different conditions merely by exchanging the thru axle. For example, to increase the stiffness of the rear-wheel axle arrangement, a 12 mm thru axle can be replaced with a 15 mm thru axle. Different wall thickness configurations of the 15 mm thru axle furthermore permit adaptation to particularly lightweight or particularly rigid rear-wheel axle arrangements.

A fourth aspect of the invention constitutes an alternative solution for referencing of the gearshift mechanism that is independent of frame tolerances. In one embodiment, the rear gearshift mechanism is suitable for coaxial installation on a rear-wheel axis. The gearshift mechanism has a base element, a linkage mechanism, a movable element and a chain guide arrangement. The linkage mechanism connects the base element to the movable element. The chain guide element is connected, rotatably about a rotary axle P, to the movable element. The base element comprises a first attachment end for coaxial installation on the rear-wheel axis and a second attachment end for coupling to the linkage mechanism. The first attachment end of the base element has a first centering opening for the purposes of directly centering the base element on a thru axle.

In one embodiment of the rear gearshift mechanism, the first centering opening is formed in a first arm of the base element.

In the operationally ready state, the first centering opening of the base element interacts directly with the screwed-in thru axle, in particular with a centering surface of the thru axle. The direct interaction of the first centering opening of the base element and the centering surface of the thru axle leads to the centering of the base element directly on the thru axle. In other words, the base element is referenced with respect to the thru axle, such that manufacturing tolerances of the frame do not have an effect on the centering of the gearshift mechanism.

In one embodiment, the base element has a second arm which is arranged so as to be spaced apart in an axial direction from the first arm. The second arm has a second centering opening. In the operationally ready state, the first centering opening of the first arm interacts with the centering surface of the thru axle and the second centering opening of the second arm interacts with the adapter, in particular with the external diameter of the bolt head of the adapter. This arrangement permits precise orientation of the rear gearshift mechanism perpendicular to the rear-wheel axis.

In one embodiment of the rear gearshift mechanism, the base element is designed to abut in the operationally ready state axially against a hub end cap. In particular, an axial hub stop surface of the first arm of the base element is designed to abut against the hub end cap.

In one embodiment of the rear gearshift mechanism, the linkage mechanism comprises at least one pivot axle which is oriented orthogonally with respect to the rear-wheel axis. The advantages of orthogonally oriented gearshift mechanisms have already been discussed in conjunction with the preceding embodiments.

A fifth aspect of the invention relates to a thru axle for screwing into a rear gearshift mechanism, in particular into a gearshift mechanism for coaxial installation as has been described above. According to the fifth aspect, the thru axle is suitable for screwing into a rear gearshift mechanism. The thru axle has a first thru axle end and a second thru axle end. The thru axle has, on an outer circumferential surface in the region of the second end, an external thread and a centering surface. The centering surface serves for the centering of the base element directly on the thru axle. In the screwed-in state, the centering surface of the thru axle interacts with a first centering opening of the base element for the purposes of directly centering the base element on the thru axle.

In one embodiment, the thru axle is of hollow form. The thru axle has a greater wall thickness in the region of the external thread and/or of the centering surface than in other regions.

A sixth aspect of the invention provides an adequately stiff and nevertheless lightweight rear-wheel axle arrangement for a bicycle (stiffness to weight ratio). This embodiment is of importance in particular for MTBs and E-MTBs. Rear-wheel axle arrangements known from the prior art exhibit a tendency for the hub axle (hollow axle) to break. This is inter alia because the hub axle is subjected to high maximum bending stresses in relation to the thru axle. It has proven to be advantageous for the acting stresses and forces to be distributed as uniformly as possible on the hub axle and the thru axle and for a breakage of one of the two components to thus be prevented. Both the hub axle and the thru axle are loaded more uniformly, and are no longer overloaded on one side. A uniform distribution is achieved in particular if the ratio of the geometrical moment of inertia of the hub axle to the geometrical moment of inertia of the thru axle is relatively balanced. The geometrical moment of inertia ratio of hub axle to thru axle lies in the range from approximately 0.8 to 1.5, and is in particular approximately 1.1. A positive effect is realized inter alia by the fact that the hub axle is subjected to compressive load and the thru axle is subjected to tensile load. The compressive and tensile stresses are superposed on the bending stresses, and partially cancel one another out.

According to the sixth aspect, a rear-wheel axle arrangement for a bicycle comprises a hub arrangement and a thru axle. The hub arrangement comprises a rear-wheel hub (also referred to as hub sleeve) which is rotatable about the rear-wheel axis, a hollow hub axle (also referred to as hollow axle), and a hub bearing arrangement. The hub bearing arrangement enables the rear-wheel hub to be mounted so as to be rotatable relative to the hub axle about the rear-wheel axis. The hollow thru axle is, for the purposes of fixing the hub arrangement to a bicycle frame, designed such that it can be inserted into the hollow hub axle and screwed into a rear gearshift mechanism. The hollow thru axle has, at least in the region of the hub bearing, a wall thickness which is dimensioned to be at least as great as a wall thickness of the hub axle.

Owing to the considerably increased geometrical moment of inertia, thru axles with an increased external diameter of 15 mm have a positive effect on the stiffness of the entire rear-wheel axle arrangement. The thru axle is likewise a load-bearing component. The increased diameter of the thru axle contributes to a balanced geometrical moment of inertia of hub axle and thru axle. In particular, rear-wheel axle arrangements have proven to be successful which have a hub axle with an external diameter of approximately 17 mm and an internal diameter of approximately 15 mm combined with a thru axle with an external diameter of approximately 15 mm. The diameter of the thru axle and of the hub axle are coordinated with one another such that the thru axle can be inserted into the hub axle with a clearance fit. The thru axle may, depending on the field of use, have for example a wall thickness of 1.5 mm (standard), 1 mm (lightweight) and 2 mm (E-bike). These configurations lead to a balanced load on hub axle and thru axle. The different thru axles may be used with the same hub axle depending on the field of use. In other words, the same hub arrangement can be inexpensively and quickly adapted by exchanging the thru axle (modular principle).

The six aspects of the invention may be considered and implemented separately from one another and in a combination of multiple aspects.

The invention furthermore relates to a bicycle drive which comprises a gearshift mechanism, a multi-sprocket arrangement with eleven, twelve or more sprockets, a bicycle chain and a chain ring arrangement with in particular exactly one chain ring. The gearshift mechanism may be electrically controlled. Likewise, in the case of multiple chain rings, the derailleur may also be electrically controlled. Wireless control of the gearshift mechanism and/or of the derailleur is particularly advantageous. Electrically controlled gearshift mechanisms commonly comprise a transmission unit and a battery. It would be possible for the transmission unit and/or battery to be arranged in space-saving fashion in a cavity of the base element, for example between the two arms of the base element. At this position, they would be protected against external action by the structure of the base element, and immovable relative to the frame.

At least one sprocket of the sprocket arrangement may have a sequence of a thin tooth, a thick tooth and a further thin tooth. Here, a thick tooth is designed to be of such a thickness in an axial direction that, although it can engage into an outer link pair of the chain, it cannot engage into an inner link pair. This has a positive effect on the chain guidance. The sequence may repeat multiple times along the circumference of a sprocket. In the case of sprockets with an even number of teeth, it is also possible for all of the teeth to be alternately thin and thick. The axial thickening may be realized either on both sides of the sprocket or only on one side. The thickening is preferably arranged only on the rear side of the sprocket. It is of particular significance in particular on the two largest sprockets, because it is there that the chain skew is at its most pronounced (cf. FIG. 11 with thick and thin teeth on the largest sprocket 12). As a result of the better guidance of the chain, the adverse consequences of the chain skew at the relatively large sprockets are minimized. The chain ring may also have alternating thick and thin teeth which serve for improved chain guidance

In an embodiment, a rear gear shifting mechanism (10) for a bicycle includes a base element (20), a linkage mechanism (30), a movable element (40), and a chain guide arrangement (50). In the embodiment the linkage mechanism (30) connects the base element (20) to the movable element (40), and the chain guide arrangement (50) is connected, rotatably about a rotary axle axis (P), to the movable element (40). In this embodiment the base element (20) comprises a first attachment end (21) for coaxial installation on the rear-wheel axle axis (A) and a second attachment end (29) for coupling to the linkage mechanism (30).

In an embodiment the rear gear shifting mechanism is configured such that the first attachment end (21) has a first arm (22 a) and a second arm (22 b), which are arranged so as to be spaced apart from one another in an axial direction.

In an embodiment, the rear gear shifting mechanism (10) is configured such that the base element (20), in particular the hub stop surface (26) of the first arm (22 a), abuts in an operationally ready state axially against a hub end cap (4).

In an embodiment, the rear gear shifting mechanism is configured such that the linkage mechanism (30) comprises at least one pivot axle (31, 32, 33, 34) which is oriented orthogonally with respect to the rear-wheel axis (A).

In an embodiment, the rear gearshift mechanism (10) is configured such that the gearshift mechanism (10), in particular the movable element (40), has an arresting element (42) which makes it possible for the preloaded chain guide arrangement (50) to be fixed relative to the movable element (40) for the purposes of setting the gearshift mechanism (10).

In an embodiment, the rear gearshift mechanism (10) is configured such that the first attachment end (21) of the base element (20) has a first centering opening (23 a) which is designed to interact in the operationally ready state with a centering surface (87, 97) of the thru axle (80, 90) for the purposes of centering the base element (20) on the thru axle (80, 90).

In an embodiment, the rear gearshift mechanism (10) is configured such that on the movable element (40) or on the chain guide arrangement (50), there is arranged an inner limit stop (59 a) which is designed to interact, in an inner maximum position of the gearshift mechanism (10), with a sprocket assembly (R) in order to limit an axial movement of the gearshift mechanism (10) in an inwards direction.

In an embodiment, the rear gearshift mechanism (10) is configured such that on the chain guide arrangement (50), there is arranged an outer limit stop (59 b) which is designed to interact, in an outer maximum position of the gearshift mechanism (10), with the base element (20) in order to limit an axial movement of the gearshift mechanism (10) in an outward direction.

In an embodiment, a rear gearshift mechanism (10) for coaxial installation on a rear-wheel axis (A) is provided. The gearshift mechanism includes a base element (20), a linkage mechanism (30), a movable element (40), and a chain guide arrangement (50). The linkage mechanism (30) connects the base element (20) to the movable element (40). The chain guide arrangement (50) is connected, rotatably about a rotary axis (P), to the movable element (40). The base element (20) comprises a first attachment end (21) for coaxial installation on the rear-wheel axis (A) and a second attachment end (29) for coupling to the linkage mechanism (30). In this embodiment the gearshift mechanism is configured such that the first attachment end (21) of the base element (20) has a first centering opening (23 a) for the purposes of directly centering the base element (20) on a thru axle (80, 90). In this embodiment, the first centering opening (23 a) is formed in a first arm (22 a) of the base element (20). The base element (20) may have a second arm (22 b) which is arranged so as to be spaced apart in an axial direction from the first arm (22 a). The base element (20), in particular an axial hub stop surface (26) of the first arm (22 a) may be designed to abut in an operationally ready state axially against a hub end cap (4). The linkage mechanism (30) may include at least one pivot axle (31, 32, 33, 34) which is oriented orthogonally with respect to the rear-wheel axis (A).

In an embodiment, a thru axle (80, 90) for screwing into a rear gearshift mechanism is provided. The thru axle having a first thru axle end (81, 91) and a second thru axle end (82, 92), wherein the thru axle (80, 90) has, in the region of the second end (82, 92), an external thread (83, 93) and a centering surface (87, 97) for the purposes of directly centering the base element (20) on the thru axle (80, 90). In this embodiment, in the screwed-in state of the thru axle (80, 90), the centering surface (87, 97) of the thru axle (80, 90) may interact with a first centering opening (23 a) of the base element (20) for the purposes of directly centering the base element (20) on the thru axle (80, 90). In this embodiment the thru axle (80, 90) may be of hollow form and may have a greater wall thickness (W86, W96) in the region of the external thread (83, 93) and/or of the centering surface (87, 97) than in another region of the thru axle (80, 90).

In an embodiment, a rear-wheel axle arrangement for a bicycle is provided. The axle arrangement includes a hub arrangement having a rear-wheel hub (3) which is rotatable about a rear-wheel axis (A), having a hollow hub axle (5) and having a hub bearing arrangement (9) for the rotatable mounting of the rear-wheel hub (3) relative to the hub axle (5). The axle arrangement also includes a hollow thru axle (80, 90) which, for the purposes of fixing the hub arrangement on a bicycle frame (1), is designed such that it can be inserted into the hollow hub axle (5) and screwed into a rear gearshift mechanism (10). The axle may be configured such that the hollow thru axle (80, 90) has, at least in the region of the hub bearing (9), a wall thickness (W85, W94 a) which is dimensioned to be at least as great as a wall thickness (W5) of the hub axle (5).

While the present invention has been described above by reference to various embodiments, it should be understood that many changes and modifications can be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description. 

1. A rear gearshift mechanism for coaxial installation on a rear-wheel axis of a bicycle, comprising: a base element, a linkage mechanism, a movable element, and a chain guide arrangement, wherein the linkage mechanism connects the base element to the movable element, and the chain guide arrangement is connected rotatably about a rotary axis, to the movable element, and wherein the base element comprises a first attachment end for coaxial installation on the rear-wheel axis and a second attachment end for coupling to the linkage mechanism, and wherein the first attachment end has a first arm and a second arm, which are arranged so as to be spaced apart from one another along the rear-wheel axis.
 2. The mechanism according to claim 1, wherein, in the installed state, the first arm is arranged on an axial inner side of a frame and the second arm is arranged on an axial outer side of the frame.
 3. The mechanism according to claim 2, wherein the first arm has a first centring opening and the second arm has a second centring opening.
 4. The mechanism according to claim 1, wherein the first arm has, on its axial outer side, an adapter stop surface.
 5. The mechanism according to claim 1, wherein the first arm has, on its axial inner side, a hub stop surface.
 6. The mechanism according to claim 1, wherein the first arm has, on its axial inner side, a hub guide.
 7. The mechanism according to claim 1, wherein the first arm has an axle opening for the leadthrough of an axle, in particular of a thru axle.
 8. The mechanism according to claim 1, wherein the base element has an attachment point for a cable diverter.
 9. The mechanism according to claim 1, wherein the base element has a first receptacle for a first pivot axle of the linkage mechanism and a second receptacle for a second pivot axle of the linkage mechanism, and wherein the first and second receptacles are each oriented orthogonally with respect to the rear-wheel axis.
 10. The mechanism according to claim 1, having an adapter which comprises a screw connection, in particular a bolt with an external thread and a nut with an internal thread.
 11. The mechanism according to claim 10, wherein the adapter is insertable into a frame opening and is fixable on the frame by the screw connection.
 12. The mechanism according to claim 11, wherein the bolt has a bolt body with a contact region and a compensation region.
 13. The mechanism according to claim 12, wherein the adapter, in particular the bolt, has an axle opening in which an internal thread is arranged, into which a counterpart thread of the thru axle can be screwed.
 14. The mechanism according to claim 13, wherein a first external diameter of the adapter is coordinated with an internal diameter of the first centring opening of the base element, and a second external diameter of the adapter is coordinated with an internal diameter of the second centring opening of the base element.
 15. The mechanism according to claim 14, wherein an external diameter of a bolt foot is coordinated with the first centring opening and an external diameter of the bolt head is coordinated with the second centring opening.
 16. The mechanism according to claim 15, wherein the adapter, in particular an axial stop surface of the bolt, bears against the axial adapter stop surface of the base element.
 17. The mechanism according to claim 16, wherein the base element has a stop and the adapter has a counterpart stop.
 18. A rear gearshift mechanism for coaxial installation on a rear-wheel axis of a bicycle, comprising: a base element, a linkage mechanism, a movable element, and a chain guide arrangement, wherein the linkage mechanism connects the base element to the movable element, and the chain guide arrangement is connected rotatably about a rotary axis, to the movable element, and wherein the base element comprises a first attachment end for coaxial installation on the rear-wheel axis and a second attachment end for coupling to the linkage mechanism, and wherein the base element, in particular the hub stop surface of the first arm, abuts in an operationally ready state axially against a hub end cap.
 19. The mechanism according to claim 18, wherein the first arm is arranged between the hub end cap and the adapter, in particular is fixed in non-positively locking fashion between the hub end cap and the adapter.
 20. A rear gearshift mechanism for coaxial installation on a rear-wheel axis of a bicycle, comprising: a base element, a linkage mechanism, a movable element, and a chain guide arrangement, wherein the linkage mechanism connects the base element to the movable element, and the chain guide arrangement is connected rotatably about a rotary axis, to the movable element, and wherein the base element comprises a first attachment end for coaxial installation on the rear-wheel axis and a second attachment end for coupling to the linkage mechanism, and wherein the linkage mechanism comprises at least one pivot axle which is oriented orthogonally with respect to the rear-wheel axis.
 21. The mechanism according to claim 20, wherein the linkage mechanism is formed as a four-joint parallelogram with four pivot axles, and all four pivot axles are oriented orthogonally with respect to the rear-wheel axis.
 22. The mechanism according to claim 21, wherein a first pivot axle rotatably connects an inner pivot arm of the linkage mechanism to an inner receptacle on the base element and a second pivot axle rotatably connects an outer pivot arm of the linkage mechanism to an outer receptacle on the base element, and the receptacles are aligned axially with the pivot axles.
 23. The mechanism according to claim 22, wherein the chain guide arrangement comprises an upper chain guide roller which is rotatably arranged with a constant upper spacing to the rotary axis, and comprises a lower chain guide roller, which is arranged rotatably with a constant lower spacing to the rotary axis. 